A Role for Astrocyte Metabolism in Species-Specific Neuronal Development

Area of Science:

• Neuroscience
• Developmental Biology
• Astrocyte Biology

Background:

• Human neurons exhibit slower development (neoteny) compared to non-human primates, with neuron-intrinsic factors being the primary focus of research.
• The role of astrocytes, a type of glial cell, in mediating species-specific differences in neurodevelopment remains underexplored.

Purpose of the Study:

• To investigate species-specific functional divergence in astrocytes and their influence on neurodevelopmental rates between humans and non-human primates (NHPs).
• To elucidate the role of astrocyte metabolism in shaping human-specific neurodevelopmental timing and trajectories.

Main Methods:

• Comparison of human and NHP organoid models to identify differences in gliogenesis timing.
• Transcriptomic and 13C metabolic flux analyses of induced pluripotent stem cell (iPSC)-derived astrocytes to determine metabolic profiles.
• Assessment of human neuron development in response to conditioned media from human versus rhesus astrocytes.
• Chemical inhibition of PHGDH to investigate the role of astrocyte metabolic pathways.

Main Results:

• Delayed onset of gliogenesis observed in human organoid models compared to NHPs.
• Distinct astrocyte metabolic profiles: NHPs show increased serine/glycine synthesis, while humans exhibit elevated lactate secretion.
• Human neurons cultured with rhesus astrocyte conditioned media showed enhanced electrophysiological maturation and altered transcriptomic development.
• Human astrocyte secretomes are enriched in synaptogenic and axon-growth proteins, suggesting a role in structural complexity over rapid maturation.

Conclusions:

• Astrocyte metabolism plays a significant cell-extrinsic role in determining human-specific neurodevelopmental timing and trajectories.
• Differences in astrocyte metabolic function, such as lactate secretion, contribute to species-specific neurodevelopmental patterns.
• Understanding astrocyte contributions to neurodevelopment offers insights into human brain evolution.